Efficacy of Er, Cr: YSGG laser phosphoric acid gel and Riboflavin activated by Photodynamic therapy on enamel reconditioning rebonded to metallic brackets: An Invitro study.

ABSTRACT

AIM: To evaluate the shear bond strength (SBS) and failure percentage of rebonded metallic brackets after employing various enamel-reconditioning methods (37% phosphoric acid, sandblasting, Er, Cr YSGG laser, and Riboflavin (RF). MATERIAL AND METHODS: After sample size calculation, a sum of 40 non-carious, non-traumatically extracted and sound human premolar teeth were collected and the enamel surface was prepped by etching, washing, and drying. The enamel surface was primed with a bonding agent and light cured, later brackets were bonded via composite. After bonding, bracket debonding was begun using a Weingart plier and the enamel surface was reconditioned before rebonding. Samples were divided into four (n=10) reconditioning groups at random and subjected to SB with 90-µm alumina particles group 1, Er, Cr YSGG laser group 2, 37% PA (control) group 3, and RF group 4 respectively. After reconditioning, brackets were rebonded to the enamel surface via an adhesive system and composite. Later, samples were exposed to the universal testing machine for SBS analysis, and bond failure analysis was performed by using an adhesive remnant index (ARI). Statistical analysis was executed by one-way ANOVA and Post Hoc Tukey multiple comparison tests at a statistically significant level of p ˂ 0.05. RESULTS: The SBS analysis showed that the highest SBS of rebounded brackets was exhibited by 37% phosphoric acid (control) and the lowest SBS by sandblasting enamel surface with 90-µm alumina particles for enamel prior rebonding. However, Er, Cr YSGG laser and RF activated by PDT validated comparable SBS results to control (p>0.05). Contrarily, sandblasting with 90-µm alumina particles showed a statistically significant difference from other analyzed reconditioning groups (p<0.05). Deliberating failure rate analysis by ARI index, the most eminent failures predicted among groups were scored between 0 and 1 except for sandblasting which majorly resulted in a score of 2 showing cohesive type failure. CONCLUSION: Chromium-doped erbium, yttrium-scandium-gallium-garnet (Er, Cr YSGG) laser, and Riboflavin activated by photodynamic therapy have the potential to be used as an alternative to 37% phosphoric acid for enamel surface reconditioning before the rebonding metallic bracket.